Associative memories or content addressable memories are well known in the art.
So far, the associative memories are more expensive than random access memories (RAM) because each cell must have a storage capability as well as logic circuits for matching its content with an external argument.
Examples of such prior art cells are described in IBM Technical Disclosure Bulletin Vol. No. 3, August 1974, page 884 and Vol. No 74A, December 1980, page 2823.
In these cells, in addition to the transistors which have to be provided, for the storage and search capabilities, search or match lines are required which leads to low density associative memories.
Furthermore, the trend of present technologies is to design embedded random access memories in very large scale integration (VLSI) chips, making it of interest to use the embedded RAM cells and to personalize the peripheral circuits to perform the read/write function.